Piano



(No Model.)

A. GRAPE.

PIANO. No. 449,933. Patented Apr; 7, 1891.

fly 4 m in 6.14 w.

- UNITED STATES PATENT OFFICE.

ALBERT GRAFF, OF SAN FRANCISCO, (IALIFORNIA.

P I A N O SPECIFICATION forming part of Letters Patent No. 449,933, dated April 7, 1891.

Application filed February 19, 1890. Serial No. 341,061. (No model.)

To all whom it may concern.-

Be it known that l, ALBERT GRAFF, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented certain new and useful Improvements in Pianos; and I do hereby declare the following to be a full, clear, and exactdescription of said invention, such as will enable others skilled in the art to which it most nearly appertains to make, use, and practice the same.

My invention relates to the sounding-board of pianos and the fram e-work which surrounds it; and it has atwofold object: first to mount the sounding-board in a suitable frame-work and provide means by which it can be readily strained to any desired tension, and, sec ondly, to combine the wrest-plank, frame, and back which surrounds the sounding-board in a single metallic casting, in which the sounding-board is placed and the straining devices applied, thus providing durability and strength and the means for giving to the sounding-board an adj ustabilit'y of tension by which it can be readily adapted to any location or climate.

The value of a piano depends upon its capaoity to sustain the enormous strain to which itis subjected by the tension of its strings or wires andthe resonant qualityof its sounding-board. I have discovered that the resonant quality of the sounding-board can be increased or diminished by subjecting it to greater or less compression or strain, and in order to provide for a proper application of straining or compressing devices I make the wrestplank, upper braces, and side strengtheningn'ibs of metal and cast them in a single piece, so that I obtain not only the requisite strength for resisting the compression of the soundingboard, but also the requisite strength for resisting or sustaining the strain of the strings or wires.

Referring to the accompanying drawings, Figure l is aback view of the sounding-board and frame adapted for an upright piano. Fig. 2 is a vertical section taken through Fig. 1. Fig. 3 is a front view, and Fig. 4 is a detail view showing the method of applying the devices for compressing the sounding-board.

Letter A represents the wrest plank in which the keys which st ain the strings or wires of the piano are held. 13 is the frame, and O the upper braces, which extend across the frame to give it support and strength. These three parts I make of metal and cast them in one integral piece, as represented in the drawings. T ie frame B, 1 cast with an inwardly-extortding flange, as shown at Figs. 2 and i, so as to provide a ledge for the sounding-board to rest upon on the inside of the frame. The sounding-board D, which is made of wood in the ordinary way, is fitted so that it will pass inside the frame and be supported on the ledge d and in the compression-keys, as hereinafter described. One corner of the frame has an angular rib f or corner-piece extending across it in the usual manner of constructing the frames of sounding-boards of pianos, and this corner-piece has a ledge similar to and corresponding with the ledge of the frame.

In the angle of the frame on one side and one end of the frame and also in the angle of the L-shaped corner-piece Iplaee two narrow plates or bars 9 g, the meeting faces of which are beveled in a reverse direction, as shown at Fig. l. The inner bar g rests upon the inner edge of the ledge cl, and it has a groove i in its inner face near its lower end, in which the edge of the sounding-board is received, while the edge of the sounding-board on the other side and end rests upon the ledge (Z and against the side of the frame. The beveled bar 9 fits between the beveled face of bar 9 and the projecting side of, the frame and is shorter than bar g, so that it does not extend entirely down to ledge d. At intervals apart a screw or bolt 7L passes through a hole in bars 9 g and is screwed into atapped hole in the ledge, so that by turning these bolts or screws the beveled bar g will be forced down between the frame-iron and the beveled bar g, and thus act as a wedge to force or crowd bar 9 inward,

thus compressing the sounding-board against the opposite side and end of the frame and giving to it any desired amount of tension. This arrangement can be applied to the sonnding boards of either square or upright IOO The sounding-boardis*-also held in a permanently rigid iiositi'on and condition, and should it from any reasonsuch as the efiects of climate or temperature-become slack or dead it can in a few moments time be strained up to the desired pitch.

Having thus described my'inventionjwhat I claim, and desire to secure by Letters Patent of the United States, is I 1. A metallic frame for the sounding-boards of pianos, provided with an inwardly-extending ledge adapted to supportthe sounding board, in combination with movable or adjustable parts for increasing the "tension" -01? said sounding-board and means for adjusting 'said parts and' fastening the soundingboard; snbstantially'as s'et forth. I 2. 'A' metallicframefo-i'soiinding boards"of pianos, provided With an iiiwardly-extendin g ledge, in combination with Wedge-blocks seated upon said l'edge; the outer "of 'said blocks being shorter than its companion, which latter "is provided with a groove, {c01npressi'onfboltm'and aQsou'nding boardhaving one endandfside fitting in -the groove of the wedge-block,substantially as set t'orth.

" the-longer one ofsaidb'loeksbeing provided with a groove, compression-bolts, and asounding-board arm-aged to be compressed by the action of the wedges and bolts, substantially asset forth.

w 4:. A metallic frame forthe sounding-boards of pianos,h'a"ving an'int'ernal ledge d, arranged 'to' support the f sounding-board, in combination with the reversed wedges or bars g g and compression-bolts h, arranged as de scribed, "for compres'singthe-soundipg-board, substantially as described.

In wi tness-where'of I have this-21st dayeofi December; 1889; set any-hand in presence of twowitn eases.

'AIJBER l GRAFF.

5 In'prese'nce of- -A-. H; STE; MARIE, F. N. BIGELOW. 

